Cameras having pan, tilt and zoom functionality are commonly used for surveillance purposes. Such cameras are typically connected, via a network, to a client device serving as a software or a hardware interface by which an operator is able to control the movement of the camera.
Due to latencies in the network, in the camera or in the client device, there will be a time delay from the time when the camera control is performed up to the time when a camera-controlled image arrives. That is, it takes time until an image reflecting the operator's control command may be shown to the operator. Since the images shown to the operator are lagging, it becomes difficult to control the pan/tilt/zoom movements. This problem becomes more severe when the speed of the pan/tilt/zoom movement is increased.
U.S. Pat. No. 6,822,676 addresses this problem in the context of zoom control. As a zoom-in control command is received, electronic zoom processing is performed in the last image received from the camera, and the electronically zoomed image is shown to the operator. When a predetermined time has elapsed, the displayed image is changed from the image undergoing electronic zoom processing to a new image transmitted from the camera.
However, a drawback of this approach is that it is limited to zoom-in. A further drawback is that the operator has to wait until he/she is presented with new image data. There is thus a need for improvements.